Hammer and buffer mechanism



March 17, 1959 messa/z5 w K. W. MAIER 2,877,750

HAMMER AND BUFFER MECHANISM Filed May 29, 1957 j Ivi-v cano/Vi 5l/Fifi Z0 JNVENTOA KARL W. MAIER HAMMER AND BUFFER MECHANISM Karl W. Maier, Cheshire, Conn., assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Application May 29, 1957, Serial No. 662,359

3 Claims. (Cl. 123-7) The present invention deals with buffer mechanisms.

AThe invention relates in particular to buffer mechanisms for piston tools of the type where hot gases or other iiuids, confined in a chamber, are impinged upon the face of a piston effective to impart kinetic energy to the piston. The energy developed in the piston is in turn utilized to drive a fastener, performing a punching or hammering operation or to do other work. In piston tools of the above general class, there is always the problem of absorbing unused or unconsumed energy re maining in the piston after a particular work stroke of the piston has been completed.

A good buffer mechanism is necessary to prevent the piston from overworking. For example, it is highly desii-able to bring the piston to a stop after the work has been completed without driving a fastener beyond tolerable limits and without setting up impact forces in the tool itself which will damage the piston or the cylinder within which the piston is housed.

Accordingly, it is a particular object of the present invention to provide a piston tool of the above general class having a novel buffer mechanism.

It is a further object of the present invention to provide a piston tool having a uid buffer mechanism.

A further object of the invention is the provision of a powder actuated piston tool having a fluid buffer mechanism.

it is a still further object of the invention to provide a powder actuated piston tool having a novel valve system.

A further object of the invention is the provision of a powder actuated piston tool having a combustion chaml ber and a compression chamber both of which are eective to buffer the piston.

A powder actuated tool embodying the principles of the buffer mechanism of the present invention may com-u prise a cylinder having a combustion chamber and a. compression chamber, a piston having two working faces slidably disposed in the cylinder, one face of the piston forming a wall of the combustion chamber and the other face of the piston forming a wall of the compressionA chamber, said piston being movable within the cylinder from a firing or battery position through a high pressure zone to a communication zone and thence to a buffer zone, the interior wall of said cylinder being; formed with a conduit of such length and of such dis-I position relative to the path traversed by the piston that; when the piston is in the high pressure zone or in the buffer zone, there is no communication between said chambers, while when the piston is in the communica-I tion zone, said chambers communicate with one another' through said groove.

Other features and advantages of the invention will. be more apparent from an examination of the following specification when read in conjunction with the appended. drawings in which:

Fig. 1 is a sectional view of a portion of a piston tool. illustrating one embodiment of the invention;

States Patent Fig. 2 is a view of a transverse section of Fig. 1 taken along the line 22;

Fig. 3 is a view of the tool of Fig. 1 and showing the piston at the end of the communication zone and at the point of entrance into the buffer zone;

Fig. 4 is a sectional view of a tool similar to the tool of Fig. 1 and showing another embodiment of the invention. The piston is shown disposed at the junction between the high pressure zone and the communication zone;

Fig. 5 is a transverse section of Fig. 4 taken along the line 5 5;

Fig. 6 is similar to Fig. 4 and shows the piston dis posed in the communication zone, and;

Fig. 7 shows the piston of Fig. 4 in the buffer zone.

Referring now in detail to the drawings and in particular to Figs. 1, 2 and 3, there is shown a cylinder 10 having bores 11 and 12. A cap 13 formed with a cartridge chamber 14 is in threaded engagement with the cylinder as at 16.

The inner face 17 of the cap, including sidewall 18, cooperate with the face 19 of a piston 21 to define a combustion chamber when the piston is in the battery or firing position (when the piston is seated against the wall 17) and to define a high pressure zone or a 'compression chamber 22 when the piston is disposed as shown in Fig. 1.

The piston is formed with a head 23 received in the bore 12 and is operative in a well known manner to drive a fastener 24 into a work piece. A

Obviously, the piston is slidable within the bore 11 and is movable from the battery position, designated by the line 15 in Fig. 3, through the high pressure zone, defined by the lines 15-20, through the communication zone, bounded by the lines 20-30, to the buffer zone designated by the lines 30-35. At the origin of the buier zone a face 26 of the piston cooperates with a corresponding face 27 and the sidewall 18 of the cylinder to define a second compression chamber 25.

It is to be distinctly understood that in the embodi ment of the invention shown, the piston is propelled by firing a cartridge 28, disposed in firing chamber 14, by any suitable means. The hot gases generated upon ring the cartridge expand to drive the piston to the right.

The piston makes a snug lit in the bore 11 and' the head 23 thereof makes an equally snug fit in the bore 12 to provide a gas seal.

It is to be noted that the inner surface of the cylinder wall is formed with three conduits or grooves 29 disposed in circumferential array and arranged generally parallel to the longitudinal axis of the cylinder or the path traversed by the piston. n

. 'Ihe gas buffer mechanism of the presentinvention operates in the following manner:

With the piston 21 disposed in the battery position, firing of the cartridge 28 will develop hot gases which drive the piston through the high pressure zone. In the course of this motion, the head 23 engages and drives the fastener 24 into the Work piece. As soon as the piston leaves the high pressure zone and enters the communication zone, the junction of which is defined by the beginning of the groove 29, a portion of the hot gases, previously confined in the chamber 22, is free to flow through the conduit 29 into the compression chamber 25. As the piston continues through the communication zone, the chambers 22 and 25 are in communication with one another through the grooves 29. As stated before, this communication permits a portion of the gases formerly confined in chamber 22 to ow for ward to the chamber Z5. As the piston is propelled through the communication zone and passes the end 31 of the conduit 29, communication between the two com- Yof the piston with respect to the cylinder.

iipression chambers is interrupted and the piston enters thebuffer zQr 1 e. V Thelinexot demarcation between the working zone and the buffer zone is defined' by the end 31 of the groove (also.i.by line 30). A portion of the Y hot gasestdevelopedwvhenthe cartridge 28.-was tired are now trapped in the chamber 25..y Continuedmotion of the piston .to the right, as viewed in Figs. l and-3, com- `1i presses the gas loading thepiston 22 to effect deceleration.

If an exceedingly high amount of unconsumed energy remains in the piston 21 `when it enters the buler zone,

the face 26 of the piston may collide with theiface 27 I of the cylinder causing the piston to rebound, In that `:et/ent, the chamber 22 also functions asfa buffer zone when the piston returns beyond the end 32 of the groove l. and .approaches the tiring position.

A suitable port 33 is formed in thecyIinder wall to permit the; main body.,of the hot gases to exhaustat any desired interval while or afterthe piston has passed through thev communication zone.

require, the only limitation therein being that the comg munication zone` defines that position of the piston wherev in. compression. chamber 22 is in communication with `compression chamber 25.

invention may be'arranged'in avariety of ways to suit various conditions of product design and appearance `without departing fromA the spirit and scope of the principles of the buier mechanism of the present invention.

What is claimed is:

1. A gas buier mechanism comprising a cylinder having a side wall and two compression chambers, a piston having at least two` working faces slidably disposed in the cylinder, one face of the piston forming a wall of one compression chamber and other face of said piston forming .a wall of the other compression chamber, said piston being movable within the cylinder from one chamber to the other, a portion of the side wall of said cylinder being relieved on the inner side thereof to provide at least one conduitucommunicating with both chambers, said piston, while in motion, cooperating with said side wall to accomplish a valve action in said conduit.

2. A gas buier mechanism for powder actuated tools ably disposedin the/cylinder, one face of the piston form- `Referring now to Figs. 4, S, 6 and 7, there-is shown f i. another. embodiment of the present .invention wherein .azcylinder 10d .havingbores 110 and 120 `houses a piston 121.

In thisembodiment .of theinvention thepistjon is l `formed with a groove 122 while the bore 110 is correspondingly formed with a groove 123 scoopedv out of the inner surface of the cylinder.

. In this embodiment of the invention the high. pressure i zone position lis defined `by that position of ,the piston withrespect to the cylinder wherein the grooves 122 and'123 are not in communicationas shown in Fig. 4.

l The communication zone is defined by thatposition of the piston wherein the two grooves 122 and 123 are in communication permitting. transfer of hot gases from the left. side of the pistonto theright side thereof (Fig. 6) while the buffer zone is dened by thatycondition of the .piston where the grooves 122. and 123 are no 3 longer. incomrnunication as shown in Fig. 7.

.. This, embodiment of `the invention operates in the same .general fashion as .the embodiment of Figs. 1, 2

and 3. However, .it is necessary to provide the piston 121 witha lug 124y receivedin a cooperating slot 126 formed in the cylinder wall to preclude relative rotation Correspondingly, an exhaust port 127 is provided.

The position of the .piston with respect to the cylinder effects a valve action operative to control Huid ow from one side of the piston to the other.

It is anticipated that the valve system of the present ber, saidpiston being movable within the cylinder from ing a wall of the combustion chamber and other face of said` pistonforming a wall of the compression chamthe combustion chamber through the 'communication zone :to the compression chamber, an interior wall of said.cylinder `being formed with at least one groove of fsuchdength `and such disposition relative to thepath traversed by the pistonV that when the piston is in either chamber there is no communication between said chamberswhile` when the piston is in the working zone said -chambers communicate with one another through said groove.

3. AA gas buier mechanism for powder actuated tools of the. piston type comprising a cylinder having two compression chambers, a piston having two working faces slidably disposed in the cylinder, one face of the piston forming -a wall of one chamber and other face of said piston forming a wall of the other compression chamber, saidpiston being movable within the cylinder from one chamber through a communication zone to the other chamber, the interior wall of said cylinder and the exterior surface of said piston being formed with at least one groove each, said cylinder groove being of a length and. relativedisposition with respect to the various positions of the piston, that when the piston is in either cham- References Cited in the file of this patent Y UNITED STATES PATENTS '2,273,095 Fitch Feb. 17, 1942 FOREIGN PATENTS 135,989 VSweden Oct. 12, 1940 

